Hypertension affects 60,990,000 Americans, but it is not equally distributed among subgroups of the population. Because of the high prevalence of hypertension and its link with leading causes of death, a very substantial impact on public health could be achieved if it could be prevented or controlled early in life. An empirical foundation that will support the development of new preventive strategies is lacking. Further, early markers of risk for hypertension have not been firmly established. This investigation will focus on blood pressure levels, cardiovascular reactivity and dimensions of anger and hostility in African-American, Anglo-American and Mexican-American adolescents. The specific aims are to: 1) investigate gender and ethnic-racial differences in blood pressure levels; 2) investigate gender and ethnic differences in cardiovascular reactivity and test hypotheses linking anger and hostility with cardiovascular reactivity; 3) quantify the extent to which levels of blood pressure occurring during the course of daily activities can be predicted by cardiovascular reactivity exhibited in the laboratory and by resting blood pressure. The sample will consist of 360 male and female adolescents II to 16 years old. Adolescent blood pressure will be measured during a physical exam, in a laboratory setting at school and with ambulatory monitoring throughout a day. Anger and hostility in adolescents will be rated with the State-Trait Anger Expression Inventory and the Cook-Medley Hostility scale, respectively. The proposed study focuses on the adolescent stage of development. Within this group, there is considerable heterogeneity in anthropometric characteristics, sexual maturation, and aerobic fitness. These variables will be measured because they are closely linked with changes in blood pressure that emerge during adolescence. These and other variables that could obscure gender and ethnic differences in blood pressure and cardiovascular reactivity will be controlled statistically. An understanding of gender and ethnic-racial differences in patterns of risk will enhance the identification of groups that should be targeted for intervention and further research. The long range goals of this research is to expand the repertoire of strategies for primary and secondary prevention of hypertension and its sequelae.